No Service

3g on T Mobile
I upgraded to 4.2.1 nine months ago and all worked well until 2 weeks ago when I started getting No Service. This happens in different locations and is random. Sometime 3 0r 4 times per day. A power off gets me back to T Mobile. I've even tried a hard boot.
Does any one have any ideas as to a fix.
Thanks
Bill

I had a friend who this happen too after he dropped it no physical damage but wouldn't hold a signal to tmobile or any carrier for that matter .. After opening it up seeing nothing wrong I reloaded and re unlocked and it fixed the problem